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Abstract:

We studied the changes in the standing balance and the EEG sources locations during quiet stance with eyes-open (EO) and sensory-conflicted stance while standing: with eyes-closed (EC – absence of vision); with eyes-open and head maximally extended (EO_HE – inadequate vestibular information); with eyes-closed and head maximally extended (EC_HE–absence of vision, aggravated by inadequate vestibular information). An increase of sway path during stance without vision was registered mainly due to increased anteroposterior sway, while in the head-extended series we found increased mediolateral sway. We also found differences in the locations of EEG sources between series with different sensory conditions, which suggest cortex involvement in a different way for solving sensory conflict from different origins, that is supported by the different postural changes, as well. The EEG sources during standing with EO were located in the medial frontal gyrus (MFG), anterior cingulate cortex (ACC), precuneus and cuneus, while the EEG sources during EC were near the same cortical areas, but the ACC source was absent. The EEG sources during EO_HE were revealed to be in ACC, precuneus and cuneus, but not in the MFG like during standing with EO. During standing with inadequate vestibular information new sources appeared in the left superior and medial temporal gyrus in both series with eyes-open and eyes-closed. During the last series, when both modalities were producing the sensory conflict, ACC source was also present but precuneus and cuneus sources were absent, compared to the series with only vestibular conflict. Our results support the hypothesis of cortical regulation of quiet stance and changes in this regulation during sensory-conflicted stance, which depends on the modality of sensory conflict.